Here’s a Good Exercise Option for Hip OA

Neuromuscular exercise was as effective as progressive resistance training (PRT) for helping people with osteoarthritis (OA) of the hip improve functional ability and reduce pain, a cluster-randomized trial showed.

Patients assigned to neuromuscular exercise, which emphasizes balance and postural control, averaged 1.5 more chair stands performed in 30 seconds (30s-CST) after 12 weeks — the exact same increase seen with 12 weeks of resistance training in the unblinded 160-patient trial, according to Troels Kjeldsen, MSc, of Aarhus University in Denmark, and colleagues.

Additionally, mean Hip Disability and Osteoarthritis Outcome Score (HOOS) values for pain increased by 9.3 points with neuromuscular exercise versus 8.6 points with resistance training (difference -0.7, 95% CI -5.3 to 4.0), reflecting decreases in pain intensity, the researchers reported in Annals of Internal Medicine.

HOOS measures of hip-related quality of life also showed the programs to be equivalent, Kjeldsen and colleagues indicated.

This appears to be the first study to compare neuromuscular exercise with other types of physical therapy for mild-moderate hip OA.

“Of note, PRT is considered the most potent intervention for increasing muscle mass, strength, and power, features that are markedly hampered in hip OA and closely related to physical function,” the researchers explained, such that this form of exercise could be expected to be more effective than less intensive programs such as neuromuscular exercise. On the other hand, previous studies had found improvements in pain and function with neuromuscular exercise. One of these was a randomized trial comparing neuromuscular exercise with usual care, but it was structured as “prehabilitation” for patients scheduled for joint replacement and thus had relatively advanced OA.

In the new trial, candidacy for hip arthroplasty was one of the exclusion criteria (along with severe obesity and morning stiffness regularly lasting 30 minutes or more). Inclusion criteria were a clinical diagnosis of hip OA with a pain episode within the previous 2 weeks that patients rated at 3 or more on a 10-point scale.

Patients were recruited from five hospitals and 10 physical therapy clinics in Denmark. As this was an open-label, cluster-randomized trial, randomization was performed at the site level. In the end, 78 patients were assigned to neuromuscular exercise and 82 to PRT.

Just under two-thirds of participants were women. Mean patient age was about 65, and body mass index values averaged 28. Some 55% had symptoms lasting more than 2 years. About half had received no prior treatment other than over-the-counter medications. Approximately 40% reported that they still engaged in at least moderate physical activity totalling 150 minutes or more per week.

Each intervention was delivered in twice-weekly, hour-long sessions. Neuromuscular exercise comprised 10 different exercises “emphasizing sensorimotor control and functional stability,” the authors explained, with progression through four difficulty levels. Resistance training involved five exercises targeting muscles in the knee and hip joints, also progressively more intense as the program continued. At the third level, participants were instructed to continue until they literally could not perform the exercise anymore; if the target number of repetitions was completed, the intensity was raised 2%-10%.

At baseline, mean 30s-CST totals were 11.6 in the neuromuscular exercise group and 11.3 among those assigned to PRT. Other performance capabilities at baseline included (all means):

• 40-meter fast walking time: 24.4 and 24.9 seconds, respectively
• 9-step stair climb time: 10.4 seconds for both
• Affected leg extension power: 1.67 and 1.50 W/kg
• HOOS pain: 58.9 and 57.5
• HOOS quality of life: 47.1 and 43.7
• HOOS activities of daily living: 64.7 and 63.4

For all of these, and other secondary measures, patients in both groups showed modest improvements, and the differences did not approach statistical significance, although numerical trends generally favored resistance training. No safety issues were identified with either program.

Only about half of patients showed at least 80% adherence and fidelity to the scheduled programs — slightly more in the PRT group than those assigned to neuromuscular exercise — but improvements were only a little greater in a per-protocol analysis versus the primary intention-to-treat population, Kjeldsen and colleagues reported.

Limitations to the study included the specific content of each program, any of which could be modified with potentially improved (or worsened) results. “Future trials should identify responders to exercise in hip OA and investigate the underlying mechanisms, which are largely unknown,” Kjeldsen’s group concluded. “High-quality trials exploring optimal content of exercise are also warranted.”

The study’s conduct in Denmark (racial-ethnic distributions were not reported but it’s probable that participants were overwhelmingly white) and its open-label design were additional limitations.

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